PURIFICATION.

209

Fig. 70.

A

Plate XXI. shows in elevation, plan, and sections, a four-way disc-valve contrived byMr. Cathels, of Shrewsbury, with views of the same applied as a bye-pass, and two sets oftwo and four purifiers.

The advantages claimed for this valve are strength and simplicity of construction, themovable parts being merely two wood-faced discs actuated by a spindle and screw to each,similar to the well-known single disc, or “ Kirkham valve;” the impossibility of sticking,as there are no ground faces or rubbing surfaces; that the direction of the flow of gas iseasily seen by the position of the screws; and that no foul gas can pass into the gas-holdersduring the changes of the purifiers, as is liable to be the case with hydraulic and othercentre valves. The diminution of the number of valves required is also claimed as anadvantage, in common with the valves of Messrs. Cockey, Walker, and Anderson, beforedescribed.

In the arrangement of four purifiers, shown in the Plate, there is a line of piping, onwhich the valves A and B are fixed, which divides the purifiers Xos. 1 and 2 on one sidefrom Nos. 3 and 4 on the other; and there are pipes which branch off, at right angles, tothe right and left respectively, on each of which there are two valves fixed. By means ofthe valves A and B the gas is made to pass through one or both purifiers on the right-handside, and then through one or both on the left-hand side, or the reverse. Or the gas maybe directed through one side only, both purifiers on the other side being shut off. By thetwo valves on each of the branch-pipes also, either of the two purifiers may be first or thelast in the order of succession, or they may be shut off. By this arrangement any two,three, or all the four purifiers can be worked together ; the gas always passing in successionfrom the foulest to the cleanest purifier, or any one may be worked singly. In the positionof the discs of the valves as shown, the gas would pass through the purifiers in the order1, 2, 3, number 4 being shut off.

Two valves connected, as shown, to two purifiers, enable both to be worked together, oreither of them singly.

In the illustration the discs are set to pass the gas through a station-meter. By reversing

2 E